A domestic steam iron has the capability to generate steam and to subsequently release this steam through outlet openings provided in the soleplate of the iron. The steam, which is applied directly to a garment being ironed, helps to diminish the ironing effort and to improve the ironing result.
Modern steam irons may come equipped with a steam rate control, for example in the form of a turnable knob or a slider provided on the iron housing. While a low steam rate setting may suffice for efficiently ironing moderately creased clothes (or patches thereof), a high steam rate setting may be selected to aid in the removal of tough wrinkles. The control allows the user at any time to select the steam rate setting that is appropriate for the (patch of) garment at hand. Practice shows, however, that some if not most users do not bother to adjust the steam rate once they have started an ironing session. Accordingly, when the maximum steam rate has been selected initially, the iron may remain set to produce larger amounts of steam than necessary for achieving a proper ironing result. Moreover, many users tend to park an iron horizontally between different ironing strokes, e.g. during garment changing or rearrangement, which results in continuation of maximum steam production during idle time.
In an attempt to put a curb on the energy wastage that is associated with such use of a steam iron, it has been suggested to fit the iron with an intuitively operated handle that controls the steam rate. See for an example of such an iron FR602293. The working of an intuitive handle may rely on the downward force that is exerted by a user's hand as he steers the iron across a garment. In general, a user will intuitively apply a larger downward force on the handle as the degree of wrinkling in a garment increases. The applied force may thus be taken as a measure of the desired steam rate. When no force is applied, for example when the iron is parked on an iron rest, the production and/or release of steam may be halted.
Although the intuitive handle seems to provide a solution to the problem of energy wastage due to unnecessary steam production, research has shown that the range of forces exerted on a handle by an ironing user varies per individual. This means, inter alia, that the minimum force that is applied during an ironing session is individual-dependent. In addition, individual users do not display consistent force-exertion behaviour across different ironing sessions either. As an intuitive handle has a minimum force threshold that must be exceeded in order to activate it, users of an iron with such a handle may not, or not at all times, automatically apply sufficient force on the handle to bring about the release of steam. Furthermore, even though the handle may thus work unsatisfactorily, it may not be possible to put the handle out of action or to override it, and to specify the desired steam rate in a different manner.